Chang'e's passive allows her to send Jade, the rabbit, back to spawn to buy items for her from anywhere on the map.
Jade, Go! requires you to buy 10 separate items using her passive
The quickest way to do this (even though it'll mess up your gold in that game a little):
Start up Arena (the best)/Joust/Etc... and walk out of the fountain.
Remember, everything has to be bought separately!
Buy:
1. 1st level boots
2. 2nd level boots
3-10. Health/Mana Potions (buy one, drink it, buy another)
The closer you are to spawn, the quicker Jade runs back to the fountain and buys. It should only take a minute or so.
Once Jade comes back with the 10th item, achievement unlocked!